Coded video signal transmitting and receiving system

Abstract

A coded video signal transmitting and receiving system comprises in combination a coding apparatus using a plurality of prediction functions and provided for a transmitter, a decoding apparatus provided for a receiver, and a coded signal transmission path, whereby a coded video signal transmitted from the coding apparatus via the transmission path is received at the decoding apparatus and decoded thereby. In the coding apparatus, from a video signal received in time series, two dimensional blocks each consisting of a plurality of picture elements which extend over a plurality of scanning lines are formed, and the video signal is delivered out in a different sequence from that of the input time series. A predictive error value per block with respect to arbitrary one of the plurality of prediction functions associated with each block is generated, and a prediction function to generate a subsequent prediction error value is designated by use of part or all of prediction error values. An optimum prediction function selected from prediction functions is determined after a predetermined time has elapsed to generate prediction signals for picture elements in the two-dimensional block sequentially in accordance with the optimum prediction function. In coding the input video signal, at least a signal representative of the optimum prediction function and the prediction error signal are compressed and transmitted via the transmission path to the decoding apparatus in which the compressed code signal is expanded for decoding.

What is claimed is: 
     
       1. A coded video signal transmitting and receiving system comprising in combination a coding apparatus using a plurality of prediction functions and provided for a transmitter, a decoding apparatus provided for a receiver, and coded signal transmission path means, whereby a coded video signal transmitted from the coding apparatus via the transmission path means is received at the decoding apparatus and decoded thereby, said coding apparatus comprising: scan converter means which forms from, a video signal received in time series two-dimensional blocks each consisting of a plurality of picture elements which extend over a plurality of scanning lines, and outputs the video signal in a different sequence from that of said input time series;   error signal generating means which generates a predictive error value per block with respect to arbitrary one of said plurality of prediction functions associated with each block;   prediction function designation means which designates a prediction function to generate a subsequent prediction error value by use of part or all of prediction error values which have been generated by said error signal generating means;   prediction signal generating means which determines an optimum prediction function selected from prediction functions produced from said prediction function designation means after a predetermined time as elapsed, and generates prediction signals for picture elements in said two-dimensional block sequentially in accordance with said optimum prediction function;   predictive coding means which performs predictive coding by use of said prediction signal and the video signal output from said scan converter means; and   code compressor means which performs compression coding for at least a signal representing said optimum prediction function and the prediction error signal delivered from said predictive coding means, to produce a compressed predictive coding signal,   said decoding apparatus comprising:   means which receives the compressed predictive coding signal sent from the coding apparatus via said transmission path means, for separating said compressed code by expansion into a signal representing said optimum prediction function and a corresponding prediction error signal;   means which receives a supplementary decoded video signal, for generating a prediction signal in accordance with a signal representing a prediction function separated by said separating means;   predictive decoding means which receives an output of said prediction signal generating means and a prediction error signal separated by said separating means, for generating said decoded video signal;   scan inverter means which transforms an output of said prediction decoding means into the video signal in said original time series.   
     
     
       2. A high efficiency video signal predictive coding apparatus using a plurality of prediction functions comprising: scan converter means which forms from, a video signal received in time series two-dimensional blocks each consisting of a plurality of picture elements which extend over a plurality of scanning lines, and outputs the video signal in a different sequence from that of said input time series;   error signal generating means which generates a predictive error value per block with respect to arbitrary one of said plurality of prediction functions associated with each block;   prediction function designation means which designates a prediction function to generate a subsequent prediction error value by use of part or all of prediction error values which have been generated by said error signal generating means;   prediction signal generating means which determines an optimum prediction function selected from prediction functions produced from said prediction function designation means after a predetermined time as elapsed, and generates prediction signals for picture elements in said two-dimensional block sequentially in accordance with said optimum prediction function;   predictive coding means which performs predictive coding by use of said prediction signal and the video signal output from said scan converter means; and   code compressor means which performs compression coding for at least a signal representing said optimum prediction function and the prediction error signal delivered from said predictive coding means.   
     
     
       3. A predictive decoding apparatus comprising: means which receives a predictive coding signal for a video signal produced from a block-formation video signal which is rearranged in a different sequence than an original time series and compressed for coding inclusive of at least a signal representing an optimum prediction function and a corresponding prediction error signal, for separating said compressed code by expansion into a signal representing said optimum prediction function and a corresponding prediction error signal;   means which receives a supplementary decoded video signal, for generating a prediction signal in accordance with a signal representing a prediction function separated by said separating means;   predictive decoding means which receives an output of said predictive signal generating means and a prediction error signal separated by said separating means, for generating said decoded video signal;   scan inverter means which transforms an output of said prediction decoding means into the video signal in said original time series.   
     
     
       4. A high efficiency predictive coding apparatus in accordance with claim 2 wherein said error signal generating means comprises: a memory for storing video signals necessary for generating prediction signals used for at least the current block and the succeeding block, said prediction signals being expressed by said plurality of prediction functions;   signal generating means which receives information specifying one of said plurality of prediction function to read out a video signal stored in an address of said memory corresponding to said information, for generating a prediction signal;   supplementing means which provides within a duration of the current block a supplementary video signal necessary for generating a prediction signal which is expressed by said plurality of prediction functions and used for said succeeding block;   prediction error value generating means which combines said memory, said signal generating means and said supplementing means, for generating an error value between the video signal from said scan converter means and the prediction signal from said signal generating means; and   error signal generating means which computes prediction error values in parallel for part or all of picture elements in said two-dimensional block with respect to arbitrary one of said plurality of prediction functions by use of a plurality of said prediction error value generating means.   
     
     
       5. A high efficiency predictive coding apparatus in accordance with claim 2, wherein said prediction function designation means comprises: error signal generating means which generates for said block a prediction error value per block with respect to specified one of said plurality of prediction functions within a unit time period;   comparison means which compares a prediction error value generated by said error signal generating means in the present unit time period with a prediction error value which has been judged smallest in the past, so as to determine a smaller prediction error value; and   prediction function designation means which indicates a prediction function used in the subsequent unit time period to said error signal generating means in accordance with the result of comparison by said comparison means.   
     
     
       6. A high efficiency predictive coding apparatus for video signals comprising: means for forming blocks each consisting of a plurality of picture elements for an input signal supplied to the predictive coding apparatus so that a high coding efficiency is obtained for moving pictures;   means for selecting a plurality of blocks used for detecting an optimum prediction function which minimizes error values for said blocks in accordance with signals supplied from a picture element storage circuit which stores video signals for one frame;   means for computing error values of a plurality of blocks from said selecting means relative to a block associated with said input signal;   deduction means for comparing a plurality of error values corresponding to said plurality of blocks so as to deduce a direction in which the error value decreases sharpest;   control means for controlling the repetition and termination of processes including selection of a plurality of blocks which are different from said plurality of blocks, computation of said error values and deduction of the sharpest decreasing direction of said error values in accordance with the result of deduction by said deduction means;   means for determining said optimum prediction function which gives the minimum error value at the completion of said selection, computation and deduction; and   means for performing predictive coding by use of the determined optimum prediction function and said input signal.   
     
     
       7. A high efficiency predictive coding apparatus in accordance with claim 2, wherein said prediction function designation means comprises: means for computing an evaluation function value from an input video signal and a video signal associated with the previous frame at positions deviating by a given vector (shift vector) from a reference point on a field which coincides with a block of the input video signal;   means for detecting the optimum prediction function in Io separate steps (Io≧2) while determining in the I-th step (I=1, 2, . . . , Io-1) the (I+1)-th group of shift vectors on the basis of an evaluation function calculated with respect to the I-th group of shift vectors and, in the Io-th step, detecting one shift vector as a displacement vector (an optimum prediction function) indicative of the displacement of the picture on the basis of the evaluation function value calculated with respect to the Io-th group of shift vectors; and   means for encoding said displacement vector.   
     
     
       8. A high efficiency predictive coding apparatus in accordance with claim 7, wherein said evaluation function value is the number of difference signals between the input video signals and the video signals associated with the previous frame at the positions deviating by a given shift vector from those of said input video signal, said difference signals exceeding a fixed threshold value. 
     
     
       9. A high efficiency predictive coding apparatus in accordance with claim 2 or 6 which comprises: means which for selection of predictive signals, compares luminance levels of picture elements associated with input video signals and divides the degree of differences resulting from the comparison into at least three groups as by assigning small degrees of differences to one small-degree group, large degrees of differences to one large-degree group, and so on, for weighting each of the groups by one quantized value;   means which accumulates the degrees of differences in terms of the quantized values with respect to the picture elements within the block, for determining the evaluation values; and   means for selecting from the evaluation values obtained with respect to said plurality of predictive signals those predictive signals capable of reducing the values thereof.